The present invention relates to a method of measuring a temperature and a temperature distribution in a specified region of a chamber, to a method of taking samples for temperature measurement, and to a method for fabricating a semiconductor device by using the method of measuring a temperature.
The fabrication of semiconductor devices includes such processes as CVD, ion implantation, heat treatment (annealing), and plasma etching whereby a film is formed on a wafer, an impurity is introduced into the wafer, a diffusion layer is formed by activating the impurity, and the film formed is patterned. These processes should be performed under proper conditions determined individually, among which is a temperature. In particular, a temperature at a certain portion of a wafer placed in a chamber and a temperature distribution over a surface of the wafer are important parameters in controlling such processes as CVD and heat treatment.
To measure a temperature and a temperature distribution during the individual fabrication processes, various methods have been adopted conventionally.
For example, a thermocouple is mounted on a chamber for performing an RTA process as a rapid thermal anneal process or on a back surface of a wafer (TC wafer). There is also known a method of measuring a temperature in a chamber by optical measurement using the detection of an IR ray.
However, the conventional methods of measuring a temperature have the following disadvantages.
In the temperature measurement method using the TC wafer, for example, the temperature of the top surface of the wafer is unknown though the temperature of the back surface of the wafer can be detected. In addition, a temperature range that can be measured is limited so that measurement accuracy reportedly deteriorates when a certain high temperature is reached (500 to 600xc2x0 C. or more).
On the other hand, the optical measurement is also disadvantageous in that accurate temperature measurement cannot be performed because of optical noise or the like produced under the influence of a plasma. Moreover, a temperature distribution over a surface of a wafer cannot be measured by merely detecting temperature values at a limited number of points.
In particular, it is difficult to perform highly reliable measurement with respect to a temperature distribution over a surface of a wafer even by using the TC wafer.
A first object of the present invention is to perform temperature measurement by focusing attention on the fact that the anneal-induced reordering process of a portion changed by ion implantation from a monocrystalline state to an amorphous region is dependent on temperature and on conditions during implantation, measuring the thickness of the amorphous region by using spectro ellipsometry or the like, and calculating a temperature from the measured thickness and thereby increase the accuracy of temperature measurement.
The present inventors have found, in an attempt to increase the accuracy of temperature measurement by using spectro ellipsometry, a close correlation between a process for increasing the accuracy of temperature measurement and an improvement in the configuration of the amorphous region. A second object of the present invention is to improve, based on the finding, conditions during preamorphous implantation which is performed for preventing channeling or as one of preliminary processes for a silicidation process.
A first method of measuring a temperature according to the present invention comprises the steps of: (a) doping an amorphous region formed in a semiconductor region of a substrate with oxygen; (b) heating the amorphous region for a given time and determining a reordering rate at which the amorphous region is recrystallized; and (c) determining a temperature of the amorphous region in the step (b) based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance.
In accordance with the method, the reordering rate during the heating of the amorphous region can be adjusted by adjusting the concentration of oxygen and temperature measurement can be performed in a desired temperature range.
The step (a) includes doping the amorphous region with oxygen such that a concentration of oxygen reaches a critical value for holding the reordering rate in the step (b) nearly constant from the initiation of the heating. Accordingly, the determination of the reordering rate, i.e., temperature measurement is performed with ease and high reliability. In
In the case where an oxide film is formed on the semiconductor region of the substrate before the step (a) is performed, the method may further comprise the step of forming, prior to the step (a), the amorphous region by implanting impurity ions into the semiconductor region.
In accordance with the method, the adverse effect of oxygen that has been knocked on by the implantation of impurity ions and entered the amorphous region can be circumvented.
Alternatively, the method further comprises the step of removing, prior to the process performed in the step (a), a natural oxide film on the semiconductor region therefrom under a reduced pressure and the step (a) is performed without exposing the substrate to an atmosphere and by holding the substrate under a reduced pressure after the step of removing the natural oxide film. Accordingly, the oxygen concentration can be adjusted reliably to a desired value.
The step (b) is performed by using spectro ellipsometric measurement of a thickness of the amorphous region, which enables in-line temperature measurement.
A second method of measuring a temperature according to the present invention comprises the steps of: (a) forming an amorphous region in a semiconductor region of a substrate by implanting therein ions of a IV group element; (b) heating the amorphous region for a given time and determining a reordering rate at which the amorphous region is recrystallized; and (c) determining a temperature of the amorphous region in the step (b) based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance.
In accordance with the method, the amorphous region can be formed without affecting the conductivity type of the semiconductor region.
The step (a) includes implanting Ge ions under such a condition that a dose is 1xc3x971015 atomsxc2x7cmxe2x88x922 or more, which provides a distinct boundary between the amorphous region and the crystal region in the semiconductor region and increases the accuracy and reliability of temperature measurement.
A third method of measuring a temperature according to the present invention comprises the steps of: (a) forming an amorphous region in a semiconductor region of a substrate by implanting therein ions of at least one of arsenic (As), phosphorus (P), a halogen element, and an inert gas element; (b) heating the amorphous region for a given time and determining a reordering rate at which the amorphous region is recrystallized; and (c) determining a temperature of the amorphous region in the step (b) based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance.
In accordance with the method, the accuracy and reliability of temperature measurement leading to an elongated maintenance period and a reduced number of semiconductor fabricating apparatus can be increased without using a corrosive gas such as GeF4.
A fourth method of measuring a temperature according to the present invention comprises the steps of: (a) forming a plurality of amorphous regions in a plurality of portions of a semiconductor region of a substrate by implanting ions therein under different conditions; (b) heating the plurality of amorphous regions for a given time and individually determining respective reordering rates at which the amorphous regions are recrystallized; and (c) determining respective temperatures of the amorphous regions in the step (b) which correspond to the individual reordering rates based on relationships between the respective reordering rates of the amorphous regions and a heating temperature, which have been prepared in advance.
In accordance with the method, the range of measurable temperatures can be widened by using the different amorphous regions having different ranges of temperatures that can be measured with high reliability. In particular, even an unknown temperature can be detected.
Preferably, the step (a) includes implanting different ion species into the plurality of portions or implanting the ions into the plurality of portions under different conditions.
The substrate is in the form of a wafer and the step (a) is performed by using a sample having the four portions composed of four regions formed by vertically and horizontally dividing the wafer into four parts in two dimensions. Accordingly, even when the temperature in a certain process step is unknown, if only one type of ions are implanted later into the entire wafer, it becomes possible to perform detailed measurement of a temperature distribution or the like over a region at which the temperature was unknown and determined based on data on the reordering rates at the four portions.
A fifth method of measuring a temperature according to the present invention comprises the steps of: (a) forming a first amorphous region in a first semiconductor region located in a top surface of a substrate by implanting ions therein; (b) forming a second amorphous region in a second semiconductor region located in a back surface of the substrate by implanting ions therein; (c) heating the substrate under such conditions that the first amorphous region is reordered and the second amorphous region is not reordered and determining a reordering rate of the first amorphous region; and (d) determining a temperature of either one of the first and second amorphous regions in the step (c) based on a relationship between the reordering rate of the first amorphous region and a heating temperature, which has been prepared in advance.
In accordance with the method, if the temperature of the first amorphous region is measured and then the substrate is heated under such a condition that the second amorphous region is reordered, temperature measurement in the two regions having different temperatures can be performed by using the single substrate. In the case of using a wafer with an increased diameter, in particular, the thickness of the wafer is increased so that, even when the wafer is heated to a temperature at which the first amorphous region in the top surface of the wafer is reordered, the back surface thereof may not reach the temperature. By using the method of measuring a temperature, however, the number of samples for measurement can be reduced.
A sixth method of measuring a temperature according to the present invention comprises the steps of: (a) forming a first amorphous region in a first semiconductor region located in a top surface of a substrate by implanting ions therein; (b) forming a second amorphous region in a second semiconductor region located in a back surface of the substrate by implanting ions therein; (c) heating the substrate to reorder the first and second amorphous regions and determining respective reordering rates of the first and second amorphous regions; (d) determining respective temperatures of the first and second amorphous regions in the step (c) which correspond to the individual reordering rates based on relationships between the respective reordering rates of the first and second amorphous regions and a heating temperature, which have been prepared in advance; and (e) determining a heat conductivity of the substrate based on a temperature difference between the first and second amorphous regions.
Since the heat conductivity of the substrate can be determined, the method allows temperature control at each portion of the substrate and provides a product device with an improved quality and a higher yield. If the diameter of the wafer is increased, in particular, the thickness of the wafer is increased so that the process steps are controlled properly by determining the heat conductivity.
A seventh method of measuring a temperature according to the present invention comprises the steps of: (a) forming an amorphous region in a semiconductor region of a substrate by implanting ions therein under such a condition that a temperature of the substrate is lower than xe2x88x9210xc2x0 C.; (b) heating the amorphous region for a given time and determining a reordering rate at which the amorphous region is recrystallized; and (c) determining a temperature of the amorphous region in the step (b) based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance.
In accordance with the method, temperature measurement can be performed with a distinct boundary provided between the amorphous region and the crystal region in the semiconductor region or with the interface having reduced roughness. As a result, the accuracy and reliability of temperature measurement is increased.
An eighth method of measuring a temperature according to the present invention comprises the steps of: (a) forming an amorphous region in a semiconductor region of a substrate by implanting ions therein; (b) annealing the amorphous region at a temperature in the range of 300 to 450xc2x0 C.; (c) heating the amorphous region and determining a reordering rate at which the amorphous region is recrystallized; and (d) determining a temperature of the amorphous region in the step (c) based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance.
In accordance with the method, temperature measurement can be performed with a distinct boundary provided between the amorphous region and the crystal region in the semiconductor region or with the interface having reduced roughness. As a result, the accuracy and reliability of temperature measurement is increased.
A first method of producing a sample for temperature measurement is performed by heating an amorphous region of a substrate f or a given time, determining a reordering rate at which the amorphous region is recrystallized, and thereby measuring a temperature of the amorphous region during the heating based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance, wherein the amorphous region formed in a semiconductor region of the substrate is doped with oxygen at a critical concentration for holding the reordering rate during the heating nearly constant from the initiation of the heating.
The method allows production of a sample which permits temperature measurement to be performed with accuracy and reliability by using a stable reordering rate of the amorphous region.
In the case where an oxide film is formed on the semiconductor region of the substrate prior to the doping of the amorphous region with oxygen, the amorphous region may be formed by implanting impurity ions into the semiconductor region from over the oxide film prior to the doping of the amorphous region with oxygen.
The method allows production of a sample which enables temperature measurement, while removing the adverse effect of oxygen that has been knocked on and entered the amorphous region.
Prior to the doping of the amorphous region with oxygen, a natural oxide film on the semiconductor region is removed therefrom under a reduced pressure and then the semiconductor region is doped with oxygen ions implanted therein. This provides a sample for specifying a temperature in which the oxygen concentration has been adjusted more precisely.
A second method of producing a sample for temperature measurement is performed by heating an amorphous region of a substrate for a given time, determining a reordering rate at which the amorphous region is recrystallized, and thereby measuring a temperature of the amorphous region during the heating based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance, wherein the amorphous region is formed in a semiconductor region of the substrate by implanting therein ions of a IV group element.
The method allows formation of a sample without affecting the conductivity type of the semiconductor region.
During the ion implantation, Ge ions are implanted under such a condition that a dose is 1xc3x971015 atomsxc2x7xe2x88x922 or more, which provides a distinct boundary between the amorphous region and the crystal region in the semiconductor region and reduces the roughness of the interface. Consequently, a sample which allows temperature measurement with high accuracy and reliability can be formed.
A third method of producing a sample for temperature measurement is performed by heating an amorphous region of a substrate for a given time, determining a reordering rate at which the amorphous region is recrystallized, and thereby measuring a temperature of the amorphous region during the heating based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance, wherein the amorphous region is formed in a semiconductor region of the substrate by implanting therein ions of at least one of arsenic (As), phosphorus (P), a halogen element, and an inert gas element.
The method achieves the same effects as achieved by the second method of producing a sample for temperature measurement.
A fourth method of producing a sample for temperature measurement is performed by heating an amorphous region of a substrate for a given time, determining a reordering rate at which the amorphous region is recrystallized, and thereby measuring a temperature of the amorphous region during the heating based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance, wherein a plurality of amorphous regions are formed in a plurality of portions of a semiconductor region of the substrate by implanting ions therein under different conditions.
The method allows formation of a sample which permits a wide range of temperatures to be measured, as described above.
During the ion implantation, different ion species are preferably implanted into the plurality of portions.
Alternatively, the substrate is in the form of a wafer and the four portions may be composed of four regions formed by vertically and horizontally dividing the wafer into four parts in two dimensions.
A fifth method of producing a sample for temperature measurement is performed by heating an amorphous region of a substrate for a given time, determining a reordering rate at which the amorphous region is recrystallized, and thereby measuring a temperature of the amorphous region during the heating based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance, the method comprising the steps of: (a) forming a first amorphous region in a first semiconductor region located in a top surface of the substrate by implanting ions therein; and (b) forming a second amorphous region in a second semiconductor region located in a back surface of the substrate by implanting ions therein.
The method allows production of a sample which permits two temperature measurements to be performed by the foregoing action.
A sixth method of producing a sample for temperature measurement is performed by heating an amorphous region of a substrate for a given time, determining a reordering rate at which the amorphous region is recrystallized, and thereby measuring a temperature of the amorphous region during the heating based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance, the method comprising the steps of: (a) forming a first amorphous region in a first semiconductor region located in a top surface of the substrate by implanting ions therein; and (b) forming a second amorphous region in a second semiconductor region located in a back surface of the substrate by implanting ions therein, wherein when respective temperatures of the first and second amorphous regions are measured, a sample which allows a heat conductivity of the substrate to be determined based on a temperature difference between the first and second amorphous regions is formed.
The method allows formation of a sample that can be subjected to temperature control for increasing a production yield in the fabrication process, which is particularly important when the thickness of the sample increases as the diameter of the wafer increases.
A seventh method of producing a sample for temperature measurement is performed by heating an amorphous region of a substrate for a given time, determining a reordering rate at which the amorphous region is recrystallized, and thereby measuring a temperature of the amorphous region during the heating based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance, wherein the amorphous region is formed in a semiconductor region of the substrate by implanting ions therein under such a condition that a temperature of the substrate is lower than xe2x88x9210xc2x0 C.
The method provides a distinct boundary between the amorphous region and the crystal region in the semiconductor region or the interface with reduced roughness. As a result, there can be produced a sample which permits temperature measurement to be performed with high accuracy and reliability.
An eighth method of producing a sample for temperature measurement is performed by heating an amorphous region of a substrate for a given time, determining a reordering rate at which the amorphous region is recrystallized, and thereby measuring a temperature of the amorphous region during the heating based on a relationship between the reordering rate of the amorphous region and a heating temperature, which has been prepared in advance, the method comprising the steps of: (a) forming the amorphous region in a semiconductor region of the substrate by implanting ions therein; and (b) annealing the amorphous region at a temperature in the range of 300 to 450xc2x0 C.
The method provides a distinct boundary between the amorphous region and the crystal region in the semiconductor region or the interface with reduced roughness. As a result, there can be produced a sample which permits temperature measurement to be performed with high accuracy and reliability.
A first method for fabricating a semiconductor device according to the present invention is a method for fabricating a semiconductor device in a semiconductor region of a substrate, the method comprising a preamorphous step of forming an amorphous region in the semiconductor region by implanting therein ions of a IV group element, wherein after the preamorphous step, at least one of the step of implanting boron ions into the amorphous region and the step of siliciding the amorphous region is performed.
In accordance with the method, the boron implantation step or the silicidation step is performed after the formation of the amorphous region without affecting the conductivity type of the semiconductor region. The method allows a shallow diffusion layer to be formed by preventing channeling and a silicide layer to be formed with excellent smoothness.
During the ion implantation, Ge ions are implanted under such a condition that a dose is 1xc3x971015 atomsxc2x7cmxe2x88x922 or more.
A second method for fabricating a semiconductor device according to the present invention is a method for fabricating a semiconductor device in a semiconductor region of a substrate, the method comprising a preamorphous step of forming an amorphous region in the semiconductor region by implanting therein ions of at least one of arsenic (As), phosphorus (P), a halogen element, and an inert gas element, wherein after the preamorphous step, at least one of the step of implanting boron ions into the amorphous region and the step of siliciding the amorphous region is performed.
The method allows a shallow diffusion layer to be formed by preventing channeling and a silicide layer to be formed with excellent smoothness without using a corrosive GeF4.
A third method for fabricating a semiconductor device according to the present invention is a method for fabricating a semiconductor device in a semiconductor region of a substrate, the method comprising a preamorphous step of forming an amorphous region in the semiconductor region by implanting ions therein under such a condition that a temperature of the substrate is lower than xe2x88x9210xc2x0C., wherein after the preamorphous step, at least one of the step of implanting boron ions into the amorphous region and the step of siliciding the amorphous region is performed.
In accordance with the method, the ion implantation step or the silicidation step is performed with a distinct boundary provided between the amorphous region and the crystal region in the semiconductor region. As a result, a shallow diffusion layer can be formed by preventing channeling and a silicide layer can be formed with excellent smoothness.
A fourth method for fabricating a semiconductor device according to the present invention is a method for fabricating a semiconductor device in a semiconductor region of a substrate, the method comprising a preamorphous step of forming an amorphous region in the semiconductor region by implanting ions therein and annealing the amorphous region at a temperature in the range of 300 to 450xc2x0 C., wherein after the preamorphous step, at least one of the step of implanting boron ions into the amorphous region and the step of siliciding the amorphous region is performed.
In accordance with the method, the ion implantation step or the silicidation step is performed with a distinct boundary provided between the amorphous region and the crystal region in the semiconductor region. As a result, a shallow diffusion layer can be formed by preventing channeling and a silicide layer can be formed with excellent smoothness.
A fifth method for fabricating a semiconductor device according to the present invention is a method for fabricating a semiconductor device in a semiconductor region of a substrate, the method comprising the steps of: forming a first amorphous region in a first semiconductor region located in a top surface of the substrate by implanting ions therein and forming a second amorphous region in a second semiconductor region located in a back surface of the substrate by implanting ions therein; and determining, in a process of heating the first and second amorphous regions, respective temperatures of the first and second amorphous regions based on respective reordering rates of the first and second amorphous regions, determining a heat conductivity of the substrate based on a temperature difference between the first and second amorphous regions, and controlling the respective temperatures of the first and second amorphous regions of the substrate.
The method allows strict temperature control in the individual process steps and provides the relationship between temperature and the thickness of a wafer having an increasingly larger diameter. As a result, there can be fabricated a semiconductor device with a high quality and an increased production yield.